Electronic time keeping system

ABSTRACT

An electronic timekeeping device includes bipolar integrated circuit implemented logic in combination with a liquid crystal display. The bipolar circuitry is configured to effectively implement logic functions with a supply voltage of only one volt. Drive circuitry is coupled to the liquid crystal display to effectively impress an a.c. voltage across the liquid crystal cell when display is required. The logic circuitry includes a transistor configured current source regulated to effectively maintain a current independent of source and load variations, enabling integrated circuit implementation without utilizing large value external resistors. The display circuitry includes logic for enabling display of the calendar date and time, reset capabilities independent of date increments are provided.

United States Patent 11 1 ,n 11 3,886,726 Williams et al. 1 June 3, 1975 [54] ELECTRONIC TIME KEEPING SYSTEM 3.750383 8/1973 Kakizawa 58/233 A [73] Assignee: Texas Instruments incorporated, C J S h S, s dacca Dallas, Tex.

[22] Filed: June 19, 1972 {57] ABSTRACT [2]] Appl 2 4 212 An electronic timekeeping device includes bipolar integrated circuit implemented logic in combination with a liquid crystal display. The bipolar circuitry is Cl 58/50 R; 58/4 58/23 configured to effectively implement logic functions 58/58; 58/85'5 with a supply voltage of only one volt. Drive circuitry f G04b 19/30; G041" 11/24; G04) is coupled to the liquid crystal display to effectively of Search 58/23 50 impress an ac. voltage across the liquid crystal cell 350M) LC when display is required. The logic circuitry includes a transistor configured current source regulated to ef- Retemnces Cited fectively maintain a current independent of source UNITED STATES PAT TS and load variations, enabling integrated circuit imple- 3,072,155 6/1972 Bergey et a1 58/50 R mentation without utilizing large value external resis- 3,596,462 8/1971 Hayes 58/127 R tors. The display circuitry includes logic for enabling 3. 0 6/1972 Dierbock 4 58/23 BA display of the calendar date and time, reset capabili- 3.69l,755 9/l972 Gifard a a e 53/50 R ties independent of date increments are provided. 3,699,703 10/1972 Zeph 53/23 R 3,733,810 3/1971 Girard 58/50 R 6 Claims, 47 Drawing Figures SUPPLY CURRENT REGULATOR FIG. 25 /6 id ssc. RESET use. FREQ" secures P RESET FIG-5 h 23 g FIGS noun RESET fi-mra RESET CLOCK SYSTEM U 22 DECODE FIGS. 6-,

U I? DRIJEF. nlspm r FIGS. 1-; 3 FIG. 3 14 2s SUPPLY CONVERTER Inventors: Clark R. Williams; Robert H.

Schnurr, both of Dallas, Tex.

Primary Examiner-Edith Simmons Jackmon Attorney, Agent, or Firml-larold Levine; Edward J.

PATENTEUJUHB ms 3.886726 SHEET 1 SUPPLY M 0 l 1.

cuimm REGULATOR FIG. 25 m DSESE'R COUNTER FIGS. 6- no.5 FIG. 6 s

CLOCK SYSTEM SEC. RESET MIN. RESET HOUR RESET DATE RESET DECODE FIGS. 6- ./-24

I? U DRIVER DISPLAY FIGS. 6-9 FIG. 3 l4 1 28 SUPPLY CONVERTER FIG. 32

alseslv'zs PATENTEUJUH SHEET w t oHwoQ am wm "BEE 0H m HDOMBOHQM Mo m wm media x5758 BEE NN V630 w zmewwm PATENTEDJUN 3 ms SHEET E55 82 58mm m wm @055 T 25 mmazpoo a T mKDOI PAIENTEBJum I575 3.886723 SHEET 8 l CLEAR CLOCK PRESET I CLOCK II|| |II|Il|llI| IIIIIIIIIIIIIIIIIII I l l I I I I I I l I I I I I I l l L I U M Fig. /0E

CLEAR PRESE'I' O O O O o PATENTEIJJUHB m5 3886726 sum 9 REF.

UNDETERMINED R CLEAR c|.oc| PRESET REF.

CLEAR CLOCK PRESET PATENTED UH I975 SHEEI MUOAO mm Ni NM PATENTEUJUEES ms 1886.726

saw 1 1 CLOCK ENAB LE ENA BLE 0 60 EN CR 2N C l NcR ENCR ENCR 0s Q --Cs6 -cs QC JUSQD {350E CLC CLCL CLCL. CL. CL.

CLEAR STATE DIAGRAM EMHHEBJU?! 3 I975 31386126 SHEET 1 2 FROM DIVIDE BY 10 COUNTER A AEBECDDEE PATENTEDJUH 3 I975 SHEET 1 3 LIQUID C RYSTA L INPUT -C INPUT LOGIC IN PU T PATENTEUJUM ms 3386726 SHEET 14 CLOCK ENA BLE C LEA TC IN-TC STA TE DIAGRAM Fig. /9 QA CLOCK ENABLE IN-TC PM'HHEDJ'J113 m5 1 5726 saw 15 FROM -1 24 COUNTER AZBECEDDE DISPLA Y SEGMENT Fig. 23

ATABEcCDEEE J Y TO I- 24 DECODER-DRIVERS PATENIEDJUII3 I975 SHEET 1| I MMBM HB Q I I. .I I. I II I I IJ in n OW m I 1. I I I I I I W2. B mnoumo m 0H m A m l I I I I II I I I I I l I I I I I I. I I I I I I I I... an zm kw zm zm zm zm zm mu v6 no no mo x0 no EHHwMm PMENTEDJULB ms 3.886726 SHEET 18 P+ ISOLA TION C3 C1 B :1

Fig. 280

Fig. 29

SUPPLY REFERENCE Fig, 30 

1. A battery operated electronic timekeeping device comprising in combination: a. current regulator means for producing constant current from a battery voltage source on the order of 1 volt; b. a frequency source; c. first circuit means coupLed to said frequency source for providing a system clock signal; d. logic means including counter means responsive to said system clock signal and operative to provide time data, said counter means being implemented by current driven bipolar integrated circuitry coupled to and driven by said current regulator means; e. display means having a plurality of display elements for respectively displaying time data, and f. voltage drive circuit means coupled to said display means and said logic means, said voltage drive circuit means being operable to impress drive voltages across said display in accordance with said time data. g. time setting means coupled to the logic means for setting the status of the respective display elements independently of the other elements.
 1. A battery operated electronic timekeeping device comprising in combination: a. current regulator means for producing constant current from a battery voltage source on the order of 1 volt; b. a frequency source; c. first circuit means coupLed to said frequency source for providing a system clock signal; d. logic means including counter means responsive to said system clock signal and operative to provide time data, said counter means being implemented by current driven bipolar integrated circuitry coupled to and driven by said current regulator means; e. display means having a plurality of display elements for respectively displaying time data, and f. voltage drive circuit means coupled to said display means and said logic means, said voltage drive circuit means being operable to impress drive voltages across said display in accordance with said time data. g. time setting means coupled to the logic means for setting the status of the respective display elements independently of the other elements.
 2. A battery operated electronic timekeeping device comprising in combination: a. current regulator means for producing constant current from a battery voltage source on the order of 1 volt; b. a frequency source; c. first circuit means coupled to said frequency source for providing a system clock signal; d. logic means including counter means responsive to said system clock signal and operative to provide time data, said counter means being implemented by current driven bipolar integrated circuitry coupled to and driven by said current regulator means; e. display means having a plurality of display elements for respectively displaying time data, and f. a dc-dc converter for producing a relatively high display drive voltage from said battery voltage and source; g. drive circuit means coupled to said display means said logic means and said dc-dc converter, said drive circuit means being operable to impress said display drive voltage across said display in accordance with said time data. h. time setting means coupled to said logic means for setting the status of the respective display elements independently of the other elements.
 3. A battery operated electronic timekeeping device comprising in combination: a. current regulator means for providing a plurality of constant current sources from a battery voltage source on the order of 1 volt; b. a frequency source; c. first circuit means coupled to said frequency source for providing a system clock signal; d. logic means responsive to said system clock signal and operative to provide time data signals, said logic means being implemented by current driven bipolar integrated device circuitry, said logic means being coupled to and driven by said constant current sources; e. display means having a plurality of display elements for respectively displaying time data, and f. voltage drive circuit mean coupled to said display means and said logic means, said voltage drive circuit means being operable to impress drive voltages across said display in accordance with said time data. g. time setting means coupled to said logic means for setting the status of the respective display elements independently of the other elements.
 4. The electronic timekeeping device of claim 2, wherein said display drive voltage is on the order of 15 volts.
 5. The electronic timekeeping device of claim 2, wherein said display means includes a plurality of liquid crystal display elements for respectively displaying hours, minutes and seconds. 